The present invention relates to wastewater systems and more specifically it relates to a method of converting a standard anaerobic septic tank to an aerobic system wherein the effluent has much improved quality. Additionally, the subject matter of this invention relates to a wastewater treatment system for new installations which are located in geographical areas where the native soils have inadequate percloating capacity as determined by a standard percloation test and also areas in which the groundwater table is very near the surface.
As is well known, standard septic tank systems for individual home wastewater treatment have been in use for over 100 years. Anaerobic digestion is the primary treatment process in the system and occurs in the septic tank. Since the effluent from septic tanks very rarely meets point source discharge requirements, a tile drain field normally serves as the final polishing step. In the tile field, the septic tank effluent is discharged through distribution pipes (tiles) to an encompassing gravel trench, or sand bed and the treated effluent percolates into the native soils where dispersion of the effluent to surrounding soils and the local ground water table occurs. If installed correctly in an area where the soils percolate adequately, these systems provide adequate domestic wastewater treatment. The septic tank's strongest attributes are their low cost and the fact that they have no mechanical parts, and therefore minimal maintenance.
Native soils which have inadequate percolating capacity, as determined by a standard percolation test, are unsuitable for tile field placement, and the septic tank treatment system becomes inadequate. Also, if the local groundwater table is very near the surface, it may come into contact with the partially treated septic tank effluent before final treatment can occur in the tile field. This situation is also unsuitable for septic tank systems. Unfortunately, millions of such septic tank systems were installed as onsite wastewater disposal systems in areas where the percolation requirements of the native soils could not be met and or the local groundwater table is near the surface.
The density of these inadequate systems, have in recent years, been shown to have imparted a large detrimental environmental impact on water supplies, and in coastal areas, on wetlands. The human health issues imposed by this impact, and the possibility of additional detrimental environmental impact which might be imparted by inadequate systems installed in new construction, have driven many states to adopt regulations associated with individual home wastewater treatment and in particular, the restricted use of septic tank systems. Two issues are currently being addressed by many states regarding individual home wastewater treatment (onsite wastewater disposal) and its environmental impact. The first is how to remediate those inadequate septic tank systems which are already in place. The second is to assure that all onsite wastewater treatment systems installed in new construction provide adequate wastewater treatment. Many states have addressed both of these issues in a single policy. As a result thereof, many states now require, for both existing systems and new construction, either: a septic tank system where the tile drain field is installed in soils capable of percolating to state defined standards and the local groundwater table is at a sufficient depth; or, the modification to or replacement of the septic tank system with a system in which the effluent leaving the last sealed tankage of the system meets state defined water quality standards.